The present invention generally relates to filtration apparatus and more specifically relates to a multi-well filtration or solid phase extraction apparatus.
Multi-well filtration/solid phase extraction assemblies are well known in the art and are used for the assay of biological liquid specimens. Conventional filtration assemblies typically comprise a filtration plate, or separation plate, having multiple wells for receiving a liquid specimen, and a collection tray having a plurality of wells for collecting filtrate. The separation plate and the collection tray are disposed in a stacked relationship such that individual collection wells are associated each with a single filtration well. A conventional multi-well filtration plate has 96 wells for performing multiple assays simultaneously. Each well typically contains a separations media, for example a filter membrane, for separating a biological component from the liquid that is introduced into the separation plate, and allowing a liquid portion of the biological fluid to filter into the collection tray.
For many applications, a multi-well filtration/solid phase extraction assembly requires vacuum, positive pressure, centrifugation or other mechanical means to force the liquid through the separations media. A vacuum box useful for vacuum processing multiple biological samples in a multi-well filtration plate is described in U.S. Pat. No. 5,205,989 and U.S. Pat. No. 5,283,039, both to Aysta. Unfortunately, the Aysta vacuum box and other conventional vacuum assemblies that are designed to process multiple samples simultaneously, are costly, thereby discouraging many users from adopting the 96-well format for sample processing.
The present invention provides a low cost interface between a multi-well separation plate and the collection plate for enabling vacuum processing of multiple samples without need for an expensive vacuum assembly.
Accordingly, a multi-well filtration and solid phase extraction apparatus is provided by the present invention which is useful for facilitating vacuum processing of liquid biological samples using conventional multi-well separation plates and filtrate or waste collection plates. Advantageously, the present invention provides effective means for simultaneously vacuum processing multiple fluid samples without the need for a more expensive, conventional vacuum box. In one particular embodiment, the present apparatus generally comprises a unique vacuum collar that is adapted to be connected to, and in an interfacing relationship with, a 96-well separation plate and a 96-well collection plate.
The separation plate generally includes a plurality of filtration wells each including an inlet portion, and a relatively narrow outlet portion forming a nozzle-like tip. The filtration wells extend through a depth or thickness of the separation plate. A separation media is provided within each of the filtration wells for filtering a biological fluid sample to be assayed. Similarly, the collection plate includes a plurality of collection wells for receiving filtrate or eluate that is discharged from an associated one of the filtration wells.
Importantly, the vacuum collar, when interconnected between the separation plate and the collection plate, defines a substantially air-tight chamber. Means are provided for connecting the chamber to a vacuum source, such as an inexpensive vacuum pump assembly. For example, a hose barb connector extending through the collar and adapted to be connected to a vacuum hose is provided. In addition, means are provided for enabling manual control of pressure differential in the chamber in order to suit a particular application.
Preferably, the vacuum collar includes means, for example a keyed structure, for ensuring alignment between separation wells and collection wells. In another aspect of the invention, the vacuum collar is adapted to place each separation well discharge tip a specified distance into each collection well to ensure that eluates or filtrates will not contaminate adjoining collection wells. In addition, the vacuum collar may include other features which ensure proper connection of the separation plate and the collection plate each time the apparatus is used, thereby eliminating possibility of error in eluate or filtrate transfer.
In one particular embodiment of the invention, a multi-well filtration apparatus is provided in which the collection plate is adapted to be directly connected to a vacuum assembly in a stacked configuration. More specifically, the collection plate includes means, including a vent opening sized and structured to receive an air-intake member of the vacuum assembly when the collection means is disposed on the vacuum assembly in a stacked relationship.